Cant Install NextCloud [Error 128]

Hi ! I want install nextcloud on my Truenas but i have a litle problem.

I can’t install it, i have the error 128.

On my truenas i have add just one pool.
For the NetMask it’s 21 because my rooter have for mask of underNetwork :


Can you help me ^^
Thanks in advance

It seems that can’t resolve the hostname, so perhaps the dns server is not set correctly. Can you login via terminal on your truenas and ping github?